DPP4 and thyroid cancer: The methylation levels of CHST2, DPP4, DUSP6, ITGA2, SLC1A5, TIAM1, TNIK, and ABTB2 were markedly decreased in thyroid cancer patients when compared with the controls, while the methylation levels of GALNTL6, HTR7, SPOCD1, CDH16 and GRM5 were significantly increased (Supplementary Table S5, Figure 8).